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stephen hawking’s universe TEACHER’S GUIDE stephen hawking’s universe Stephen Hawking’s Universe and this guide are made possible by: Alfred P. Sloan Foundation The Arthur Vining Davis Foundations The Corporation for Public Broadcasting Public television stations

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stephen hawking’suniverseT E A C H E R ’ S G U I D E

stephen hawking’suniverse

Stephen Hawking’s Universe and thisguide are made possible by:

Alfred P. Sloan Foundation The Arthur Vining Davis FoundationsThe Corporation for Public BroadcastingPublic television stations

program schedule

Dear Educator,

All of us at Amgen are delighted to share with you the wonderful PBS series StephenHawking’s Universe. This Teacher’s Guide will provide you with valuable assistance as youtake your students on what we think will be the television experience of their lives.

The English physicist Stephen Hawking is an extraordinary person. This six-part televi-sion series, full of cosmic fireworks and provocative ideas, reflects his brilliance andinsight. Through Hawking’s exceptional mind your students will explore the questionsand theories surrounding the big bang, black holes, our model of the universe, and thetechnologies which have shaped our evolving vision of the cosmos.

As the world leader in biotechnology, we at Amgen are especially proud to be a part ofthis important educational event because our company and the biotechnology industryhave a great stake in the quality of education in our country. This nation’s competitiveposition in science and technology rests on our ability to keep a steady and reliablestream of gifted young Americans in science and technical careers. And that’s why Amgenhas been committed to devoting so much time, effort, and resources to education.

We are grateful to you in helping our nation’s students seek the limitless opportunitiesand the wonders of the universe that are before them. I hope you enjoy Stephen Hawking’sUniverse as much as we enjoy bringing it to you.

Sincerely,

Gordon M. Binder

PLEASE CHECK LOCAL LISTINGS FOR BROADCAST DATES AND ANY SCHEDULING CHANGES.

“Seeing is Believing” Monday, October 13“The Big Bang” Monday, October 20“Cosmic Alchemy” Monday, October 27“On the Dark Side” Monday, November 3“Black Holes and Beyond” Monday, November 10“An Answer to Everything” Monday, November 17

Gordon M. BinderChairman and Chief Executive Officer

Amgen1840 DeHavilland DriveThousand Oaks, CA 91320-1789

Visit the Stephen Hawking’s Universe web site at wNetStation, http://www.wnet.org, or at http://www.pbs.org.

AcknowledgmentsThis guide was produced by

Educational Resources CenterRuth Ann Burns, Director

Project Director: Robert A. MillerSupervising Editor: David Reisman, Ed.D.Design/Art Direction: vanOsGraphics: Justin MalkoWriters: Malcolm H. Thompson

Jonathan D. RameauPhoto Researcher: Christina L. DraperCopy Editor and Proofreader:

Shannon Rothenberger

Adviser: Roy Gould, Education Analyst, Smithsonian Astrophysical Observatory

Stephen Hawking’s Universe is aThirteen/WNET/Uden Associates/David FilkinEnterprises co-production in association with BBC-TV.

Funding for Stephen Hawking’s Universeand this guide are made possible by:

Alfred P. Sloan Foundation The Arthur Vining Davis FoundationsThe Corporation for Public BroadcastingPublic television stations

Copyright © 1997 Thirteen/WNET

Ordering InformationStephen Hawking’s Universe is available on videocassette from PBS Home Video. To order, call 1-800-645-4727. To purchase for educational use, call 1-800-424-7963.

A companion book, Stephen Hawking’sUniverse: The Cosmos Explained by David Filkin, the series producer and a fellow student of Hawking at Oxford, is available at bookstores for $30. Published by Basic Books.

Videotaping RightsOff-air taping rights of Stephen Hawking’s Universe are available to educators for one year following each broadcast release.

What is our place in the universe? What existed at the beginningof space and time? Where did the universe come from — andwhere is it headed?

Throughout history, imaginative mathematicians and scientistshave sought the answers to these fundamental questions.Copernicus, Galileo, Newton, Einstein, Hubble, and others useddirect observation, reasoning, applied mathematics, and newtechnologies to overturn ideas about cosmology that were oncedeemed fundamental truths. Their breakthroughs reshaped sci-ence’s understanding of the nature and structure of the uni-verse. Their work, and that of other important cosmologists,not only provided new explanations of the universe, but alsoraised seemingly paradoxical questions. Did the vast variety andmass of matter that make up the cosmos evolve from nothingbut energy? If so, where did the energy that created all of thematter in the universe come from?

The history of cosmology is a detective story in which each dis-covery leads to even more puzzles. Yet each step brings scien-tists closer to cosmology’s ultimate goal — a single theory thattakes into account all the forces shaping the universe.

Stephen Hawking’s Universe is a six-part public televisionseries that invites viewers to take part in this voyage of discov-ery. Hosted by renowned Cambridge University mathematicsprofessor Stephen Hawking, the program features notedastronomers, mathematicians, cosmologists, and physicists whoprovide an overview of the history of cosmology and the con-temporary challenges faced by astronomers.

The first program in Stephen Hawking’s Universe, “Seeing isBelieving,” shows the radical revisions that have taken place incosmology in the last two thousand years. The second, “TheBig Bang,” describes the controversies surrounding the bigbang theory. The third, “Cosmic Alchemy,” examines theoriesconcerning the evolution of matter. The fourth, “On the DarkSide,” looks at the role that cold, dark matter plays in the uni-verse. The fifth, “Black Holes and Beyond,” discusses the enig-matic objects that result from a star’s catastrophic gravitationalcollapse. The final program, “An Answer to Everything,” exam-ines scientists’ attempts to develop a complete theory of howthe universe works.

introduction

contents

How to Use This GuideThis teacher’s guide offers the following components:• Program summaries that give background information and

brief synopses of the programs;

• Previewing activities that familiarize students with the subject;

• Vocabulary that gives definitions of terms used in each pro-gram;

• Postviewing activities that correspond to the program viewed,and require students to use mathematics, research and writ-ing skills to examine issues and ideas discussed in StephenHawking’s Universe;

• Biographies of important figures in the history of cosmology;and

• Web sites on related topics.

Please Note: Each page in this guide can be photocopied anddistributed to students before viewing a program, or can beused as background information for developing lessons. Pleasetailor the use of these materials to meet your classroom needs.

Stephen Hawking’s Universe can be used in both mathematicsand science classes. We encourage you to share these materialswith your colleagues.

“Seeing is Believing” 2

“The Big Bang” 3

“Cosmic Alchemy” 4

“On the Dark Side” 5

“Black Holes and Beyond” 6

“An Answer to Everything” 7

Biographies 8

▲1

Activity aEratosthenes (276-194 BC) measured the circumference of theearth using an ingenious technique. You can use this techniquetoday with modern data.

1) On a piece of lined paperdraw two intersecting lines.

2) With a protractor measurethe angle each drawn linemakes with one of the paral-lel printed lines. The linesrepresent parallel rays of sun-light.

3) Subtract one angle from theother.

4) Now measure the angle where the two drawn lines intersect.It should equal the difference between the two angles.

5) Make a general statement describing your findings.

Activity bThe sun’s rays are parallel. Below are data taken when the sunwas highest in the sky on August 1st in Omaha, NE and in Tulsa,OK, 355 miles directly to the south. In both cities a stick wasdriven straight into the ground, and the angle that the sun’sparallel rays made with the top of each stick determined. Thesticks are extensions of the earth’s radii. From the data andknowledge that there are 360 degrees in a circle, you can use asimple algebraic equation to calculate the circumference of theearth.

Web SitesGalileo: http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Galileo.htmlNewton: http:// www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Newton.htmlEinstein: http:// www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Einstein.htmlHubble: http:// www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Hubble.html

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seeing is believingVocabularyuniverse: the totality of all things.geocentric universe: an earth-centered model of the universe.heliocentric universe: a sun-centered model of the universe.

Program SummaryFrom the dawn of civilization, humans have struggled to under-stand the nature of the universe. The ancients sought answersfrom pure reason limited by beliefs in gods and an earth-cen-tered universe. Eratosthenes’s determination of the earth’sradius and Ptolemy’s system of planetary motion shed no lighton more fundamental issues. In the Renaissance, Copernicus,Kepler, Galileo, and Newton sparked a revolution in thought.They added measurement and the concept of universal physicallaw to reason and supposition. Science was born, initiating dis-coveries which, in 1927, brought Edwin Hubble to a Californiamountaintop observatory with the right question and the meansto answer it. The interpretation of his results was astounding:the entire universe was expanding from an explosive momentof creation — the big bang.

Before Viewing the ProgramDivide into groups of three, each group taking responsibilityfor researching the individuals on one of the lists below (somegroups will have the same list). Each member of the classshould research the dates and major achievements of one per-son on the list. Present your findings to the class. What do thepeople on the list have in common? What do the lists have incommon? What is different about the historical periods repre-sented by each list (Greek, Renaissance, modern)?

List 1 List 2 List 3Eratosthenes Ptolemy Aristotle

Magellan Copernicus NewtonYuri Gegerin Hubble Einstein

Each member of the class can also research the achievementsof Galileo. Discuss what he has in common with the people oneach of the lists.

Those who researched Eratosthenes can do the earth-measur-ing activity in advance and then act as mentors for a wholeclass activity before or after viewing the program.

▲2

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Vocabularyastronomy: the study of the universe beyond the earth.cosmology: the study of the large scale structure and origin of theuniverse.

Program SummaryMany scientists of the early 20th century, including AlbertEinstein, found the idea of an expanding universe with anabrupt origin unpalatable. They viewed the universe as staticand eternal. Ironically, the most vocal advocate of the expand-ing universe was Father LaMaitre of the Roman CatholicChurch, the institution that had once strenuously resistedGalileo’s ideas. Were the same human constraints that plaguedearlier astronomers present in modern times? To a certainextent they were, but now there was a difference. All scientistsagreed that the controversy could only be settled by direct andprecise measurements. What measurements? For almost 40years a debate raged until Robert Dicke proposed that the bigbang would have produced a flash of light still present every-where as a glow of radio waves. In 1965 Arno Penzias andRobert Wilson unmistakably found that glow, now called theCosmic Microwave Background Radiation (CMBR). The debatewas over. Our universe, the totality of all things, had a fierybeginning about 15 billion years ago.

Before Viewing the ProgramIn preparation for the viewing of “The Big Bang,” discuss whatyou believe about an origin to the totality of all things. In view-ing the program, try to identify the fundamental nature of thedebate described. How was the controversy settled?

After Viewing the ProgramContinue discussing the origins and the history of our view ofthe universe. Hold a conversation on the Hubble measurementsand their interpretation. Then do the following activity and dis-cuss the 15-billion year result. This result assumes that thegalaxies have been traveling at a constant velocity. What if gravi-ty has been slowing them down? (The universe would appear tobe younger than calculated in the activity.)

the big bang

Web SitesMAP Introduction to Cosmology Page: http://map.gsfc.nasa.gov/html/web_site.htmlCosmology and the Big Bang: http://csep1.phy.ornl.gov/guidry/violence/cosmology.html

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ActivityBetween Newton and Hubble, astronomers came to realize thatthe sun was not in the center of the universe. It was just one ofbillions of stars in our galaxy. Then Hubble found that ourgalaxy was one of billions of galaxies in the universe. With hiscolleagues, he also found that every other galaxy was speedingaway from us, and that the speed seemed to be proportional toits distance. That is, if one galaxy is twice as far away as anoth-er, it is moving twice as fast, three times as far, three times asfast, and so on. This leads to a startling conclusion. You canarrive at the same conclusion by looking at the following data.

Distance (light years) Speed (light years/year)

30,000,000 0.00260,000,000 0.00490,000,000 0.006

If we know how far an object is away from us, and how fast itis speeding away, then we can calculate how long ago it left ourneighborhood. We do it by dividing the distance by the speed.Do it now for all three galaxies. Record your results. Hubblebelieved that the universe, of which our galaxy is a part, was ina general state of expansion. From a result similar to yours, thebig bang origin of the universe was conceived. Write a briefparagraph on how your result could lead to the idea of abeginning of the universe at a single point in time.

▲3

▲4

ActivityEach element gives off a unique pattern of light colors (wave-lengths) by which it can be identified. Scientists use a devicecalled a diffraction grating to observe the pattern. Its surface issimilar to the reflective surface of a CD, except the grooves areparallel. You can see the component wavelengths of light byholding a CD at just the right angle — you see a rainbow. Youcan actually analyze some light sources in the following way.First, cut a slit in a piece of dark construction paper about 2millimeters wide and 3 centimeters long. Holding a CD underthe slit paper at about a 30 degree angle (some adjustmentneeded), you will see a spectrum (rainbow) reflected on theCD. The spectrum you get depends upon the light source. Pointit at the sun or at a normal incandescent light, and you will seea continuous spectrum. If you point it at neon signs in storewindows, you will see the line spectrum of whatever gas orgases are in the tubes (except for red, most have mercury forbrilliance).

Web SitesWebElements: http://www.shef.ac.uk/uni/academic/A-C/chem/web-elements/web-elements-home.htmlWhat is the Periodic Law and how was it formulated?: http://edie.cprost.sfu.ca/~rhlogan/periodic.htmlA Little Nut: http://www.xmission.com/~dparker/nucleus.htmlThe Day the Universe Went All Funny:http://www2.ncsu.edu/unity/lockers/users/f/felder/public/kenny/papers/relativity.html

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cosmic alchemyVocabularyhot big bang: theory supported by Edwin Hubble that the universeoriginated at a single point in space and time.spectroscope: a device that divides light into its component wavelengths (colors), used to determine the chemical makeup of a dis-tant object.

Program SummaryWhat is the universe and everything in it made of? Where doesit all come from, and how do we know? Discoveries in the late19th century revealed that the entire observable universe ismade of the same elements as those on earth. With knowledgeof the dual nature of matter and energy, scientists began to fitthe pieces of the macroscopic and microscopic world together.This program covers the discovery of the nature of matter, itsinitial creation from the primordial conditions in the big bang,the building up of elements in stars, and the way this mightaffect the end of the universe.

Before Viewing the ProgramDiscuss the question of the elemental composition of the uni-verse. How do we know what elements are in the universe? Dothe spectroscopy activity and focus on the identification of ele-ments from a distance. If the matter is glowing (a star), we candetermine its composition.

The same laws governing atoms on the earth permeatethroughout the universe, just as gravity does. These are the fun-damental assumptions of modern astronomy. They allow us totheoretically apply the results of experiments here on earth tothe entire universe.

light source

compact disk

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▲5

on the dark side

Web SitesA Primer on Dark Matter: http://csep1.phy.ornl.gov/guidry/violence/darkmatter.htmlCosmic Hide and Seek: The Search for Missing Mass: http://www.gti.net/cmmiller/drkmttr.html

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ActivityThe velocity of an orbiting object is controlled by the amount ofmatter (mass) within the orbit and the radius of the orbit: thegreater the mass, the more gravity, the higher the velocity. Thegreater the radius of the orbit from the center, the lower thevelocity. This relationship is described by Newton’s equation

where Vorb is orbital velocity, M is mass, G is the constant ofgravity, and R is the radius (distance) from the center. Morethan 99 percent of the mass in the solar system is concentratedin the sun. Therefore, the sun’s gravity controls the orbitalspeeds of the planets. Here is a graph of the orbital speeds ofthe planets against the distance of the sun.

Within the whirling disk of the galaxy the velocities of orbitingstars remain roughly constant with increasing distance from thecenter. This is because the mass of the galaxy is spread out (asR increases, M increases as well because more and moremass is included in the orbits.) But when we come to the edgeof the visible mass in the galaxy, we expect the orbital velocityof outlying stars and satellite dwarf galaxies to get smaller. VeraRubin found that that was not the case.

Using the equation and your knowledge of dark matter, pro-pose an explanation for the observed high orbital velocities.

Vocabularydark matter: matter in space known to exist only from indirectobservation of its gravitational effects.radio telescope: device used to collect radio waves — a nonvisibleform of light — emitted by distant objects.

Program SummaryAccording to the observational research of Vera Rubin on thevelocities of stars around galaxies, there is a great deal of mat-ter exerting a gravitational force that we simply cannot see.This matter appears to be of an entirely different nature fromthe ordinary matter we experience, observe, and interact within everyday life. There is no spectral evidence of its presence.This “dark matter” makes up roughly 90 percent of the stuff inthe universe, and it has important gravitational implications forthe future of the universe. Specifically, will the universe keepexpanding forever, or will it someday stop and start collapsingupon itself on the way to a big crunch? Perhaps there is justenough matter for the expansion to be halted by gravity, but notenough to collapse. For science there are two problems here:What is the mysterious dark matter? How much of it is there?

Before Viewing the Program1. Here are the levels of organization of observable matter inthe universe.

1. subatomic particles 6. solar systems2. atomic nucleus 7. galaxies3. atom 8. galaxy clusters4. molecule 9. galaxy superclusters5. planets or stars

Do research in pairs on each with regard to size and the forceholding the matter together.

After Viewing the ProgramDo the following activity to examine the dark matter problem ingalaxies. What Vera Rubin found was that even beyond the edgeof the galaxies, velocity was constant, indicating large amountsof unseen mass.

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ActivityAny mass, if squeezed down small enough, can become a blackhole. To make the earth into a black hole it would have to besqueezed down to a radius of .86 centimeters, about half thesize of a golf ball. To calculate the radius of the black hole forthe mass of the earth, the equation used is:

where for the earth Me=5.8*1027grams, G=6.67*10-8,Re=6.4*108cm and c=3*1010cm/sec.

If you could weigh a thimbleful of the black hole/earth, howmuch would it weigh?

Classical physics predicts that the radius of a black holeincreases in exact porportion to an increase in mass (if anobject is twice the mass of the earth, it would have twice theearth’s black hole radius). What would the black hole radius ofthe sun be, given its mass of 334,672.02 units of earth mass?

At the center of each galaxy, a black hole with a mass of a mil-lion to a billion (106-109) times the mass of the sun is believedto reside. What black hole radius would such massive objectshave? There are 160,000 centimeters in a mile.

The radius of our solar system is roughly 6*1014 centimeters,or about 3.75*109 miles. How do the radii of these massiveblack holes compare to the radius of the solar system?

Web SitesWhat Feeds the Monster?: http://zebu.uoregon.edu/1996/ph123/qso.htmlHubble Surveys the “Home” of Quasars: http://www.xs4all.nl/~carlkop/quasars.htmlBeyond the Event Horizon: An Introduction to Black Holes: http://bradley.bradley.edu/~dware/blkhole.html

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black holes and beyondVocabularyblack hole: gravitationally collapsed object from which not even lightcan escape.quasar: stands for “quasi-stellar” object; energetic galactic nuclei.

Program SummaryThe universe is a strange and violent place, full of regionsspewing out energy on an unimaginable scale and objects somassive not even light can escape from them. With the discov-ery of quasars (extremely luminous, compact objects in thehearts of ancient galaxies), the picture of the universe becamemore complex. Though the mechanism responsible for suchenormous outputs of energy is not completely established, oneanswer was found in a part of Einstein’s theory of relativity —black holes, specifically supermassive black holes at the cen-ters of distant galaxies. These objects consume enormousamounts of matter. As the matter falls inward, it releases a largeamount of observable energy. Einstein didn’t think black holeswere possible, despite the fact that his own theory implied theirexistence. Robert Oppenheimer thought otherwise and set outto prove the presence of collapsed stars so massive not evenlight can escape them. Black holes seem to be a reality.

Before Viewing the ProgramBlack holes are so strange, they almost seem to be from sci-ence fiction. While understanding the details of space and timein the neighborhood of a black hole requires knowledge ofgeneral relativity, their essence is relatively easy to grasp.

Review the introduction to the black hole activity, then do athought experiment. “Suppose, in our imaginations, wesqueeze the earth down to half its present radius. Whathappens to the surface gravity? What happens to thevelocity required to escape?” They both increase. Nowsqueeze it to half again, and again. At some radius thevelocity required to escape will exceed the velocity oflight (c). The earth will be a black hole.

R=2MGC2

Artist’s illustration ofmatter from ared giant star

being pulledtoward a black

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Vocabularyquantum mechanics: theory describing the properties of the atomicand subatomic particles.relativity: Einstein’s theory of space and time describing gravity andthe large scale operation of the universe.

Program SummaryScientists generally agree on the big bang origin of the universeas we see it today. Fifteen billion years ago there was a momen-tous event whose nature is uncertain. But as we track theexpansion backward, toward that moment of seeming creation,the details blur. Is our universe a minor event in an endlessseries of universes (or multiverses)? Our physics seem inade-quate to explain the early times in a way that is consistent withthe conditions existing today. That is a crucial requirement ofscience — no gaps should exist in the cause-and-effect chainlinking two moments in a physical history. If our physics fails,understanding on the most fundamental level weakens; we havea crisis in science. New tentative and remarkable theories unit-ing relativity and quantum mechanics have been proposed —inflation theory and superstring theory. They are strange, notyet worked out, but seem to shed light on the earliest times.They hold the promise of providing a simple and elegant way toexplain everything in universe and how it all works.

Before Viewing the ProgramDiscuss the following: If all the matter and energy in the uni-verse are packed into a very small volume, the result fits thecharacteristic profile of a black hole. Then how could it expand?(While physicists have been able to explain this using mathe-matics, there is no simple, clear verbal explanation for it yet.)

an answer to everything

Web SitesMeasurement in Quantum Mechanics FAQ: http://www.mtnmath.com/faq/meas-qm.htmlBeyond the Big Bang: http://www2.ari.net/home/odenwald/anthol/beyondbb.htmlMathematical Breakthroughs Establish God’s Extra-Dimensional Might:http://www.surf.com/~westley/4q95faf/4q95dmsn.htmlSuperstring Theory: http://www.lassp.cornell.edu/GraduateAdmissions/greene/greene.html

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ActivitySelect one or more of the topics below, and write an essay onthe topic, citing examples from Stephen Hawking’s Universe.

1. Nature stands mute on itself; progress toward explainingeven the simplest process in the universe begins with a pro-posal. Describe the role of imagination in science in generaland in the history of cosmology in particular.

2. What makes science, science? As bizarre theories on theearly history and ultimate fate of the universe appear, somehave asked if physics is moving toward metaphysics.Describe the role of measurement in science and why itapplies to all new views of the universe.

3. Mathematics is an abstract subject. But from Galileo andNewton to today’s cosmologists, advances toward under-standing the fundamental aspects of the real universe couldnot have been made without mathematics. Describe the roleof mathematics in science in general and how it connects tothe real physical world.

Select all of the above topics and, incorporating the notions ofobservation and/or experiment, describe how science is done.

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Albert EinsteinEinstein, born March 14, 1879, ismost famous for his general theory ofrelativity and the equation E=mc2.Published in 1915, it proposed a newway to look at gravity and the opera-tions of the universe on a large scalein relation to space and time. In addi-tion to his theories of special and gen-

eral relativity, he also established the quantum nature of light,for which he received the Nobel Prize in 1921. His theorieschanged our view of the universe from that of the Newtonian“straight line” physics to that of a curved, warped space-timewith many bizarre implications. He ended his career atPrinceton University and died on April 18, 1955. Until the endof his life he was devoted to discovering a theory that coulddescribe everything in the universe, large and small, but henever realized this dream.

Edwin HubbleEdwin Hubble was born November 20, 1889. His contributionsto our understanding of the universe came in two parts. He wasthe first to determine by precise measurement the distances ofgalaxies, establishing that they were great but comparablegalaxies in their own right, not objects in the Milky Way. Withcolleagues he went on to measure the velocities of these galax-ies and found that they were all moving away from us. The fur-ther away a galaxy was, the faster itmoved. This velocity-to-distance ratiowas a straight-line proportion. UsingEinstein’s prediction that nothing inthe universe can move faster than thespeed of light, he arrived at the con-clusion that at some point in spaceand time there was a physical begin-ning to the universe, the big bang,and that the universe had beenexpanding ever since.

He found the velocities of the galaxies to be in exact proportionto their distances, which he interpreted as evidence of the gen-eral expansion of the universe. Looking backward in time, onearrives at the inescapable conclusion that all the matter in theuniverse was concentrated at a single point. Hubble’s workunderlies all of modern theory of cosmology. He diedSeptember 28, 1953.

BiographiesNicolaus CopernicusCopernicus, born February 19, 1473in Torun, Poland, first proposed thatthe sun, rather than the earth, was atthe center of the universe. This revo-lutionary idea completely contradict-ed the teachings of the RomanCatholic Church, which dominatedscholarly and religious thought inEurope at the time. His proposal was

suppressed. Copernicus’s heliocentric universe (pictured) wasa giant leap forward in our understanding of our place in thecosmos. He died May 24, 1543 in Poland.

Galileo GalileiGalileo, born February 15, 1564 in Pisa,Italy, helped bring Copernicus’s helio-centric universe into wide acceptance,despite the protests of the church. Usingthe recently invented telescope, he dis-covered the phases of Venus, thecratered and mountainous surface of themoon, Jupiter’s moons, and sunspots. Heused these observations to support theCopernican view, for which he faced theInquisition. Galileo’s application ofmathematics to describe the motion of objects was seminal insetting the course of modern science. He died under housearrest January 8, 1642.

Sir Isaac NewtonAlmost exactly one year after Galileo died in Italy, Sir IsaacNewton was born January 4, 1643 in England. He is consideredto be the founder of modern science. Newton engaged in awide range of experimental and theoretical activities, includingmathematics, optics, the nature of light, alchemy, and the cre-ation of a set of laws to describe motion. His crowning achieve-

ment was his law of universalgravitation. He proposed that thesame gravity causing objects tofall on the earth held the moonin orbit. Then he made the greatconceptual leap: that the laws ofphysics were the same every-where in the universe. He diedMarch 31, 1727 in England.

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Stephen HawkingStephen Hawking was born January 8,1942 in Oxford, England, into a scien-tific family; his father was a prominentresearch biologist. He decided early toenter science but rejected biology formathematics and physics. After receiv-ing his bachelor’s degree from Oxford,Hawking briefly considered a career inastronomy but resolved instead tostudy cosmology at Cambridge. He was

drawn to cosmology, he has said, because it asked “the reallybig question: Where did the Universe come from?”

While studying at Cambridge, Hawking developed amyotrophiclateral sclerosis, more commonly known as Lou Gehrig’s dis-ease. The illness attacks and disables skeletal muscles andaffects such basic functions as speech and swallowing. TodayHawking depends on a motorized wheelchair for mobility and,because a tracheotomy injured his vocal chords, “speaks”through a voice-processing program that responds to words hekeys into a specialized portable computer.

He received his Ph.D. from Cambridge in 1966 and collaborat-ed with his colleague, Roger Penrose, to refine the mathemati-

cal approach to black holes they had already developed.Working alone, with Penrose, and with other collaborators,Hawking developed a series of papers on related topics, suchas the beginning of time and the theory of “supergravity,” whichhas clarified certain issues surrounding the development of theso-called grand unified theory, the “theory of everything.” Thediscovery in the past few years of apparent black holes (includ-ing one at the center of our own Milky Way galaxy) have helpedto focus public attention on Hawking’s work.

Professor Stephen Hawking holds the post of LucasianProfessor of Mathematics at Cambridge, a chair once held byIsaac Newton. His calculations regarding the nature of blackholes — collapsed stars so massive they absorb whatever lightthey emit and devour the matter that surrounds them — aregenerally acknowledged to have increased science’s under-standing of how the universe began and to have advanced theprospect of a unified field theory that will unite the interactionsof the four basic forces in the universe.

His 1988 book, A Brief History of Time, sold more than eightmillion copies worldwide. Stephen Hawking has received manyhonors, including the Albert Einstein Award and the MaxfieldMedal.

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...The questions are clear and deceptively simple,

but the answers have always seemed well beyond our reach —

until now.”

— Stephen Hawking

“Where did we come from? How did the universe begin?

Where are we going?

Why is the universe the way it is?

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